While the AMG CL63, the normally aspirated V-8 hot-rod version of the Mercedes-Benz CL coupe, was certainly a head-turner with its 518 bhp and 465 lb.-ft. of torque, those with a hankering for a bit more punch will be rewarded for their patience by waiting for the launch of the CL65, the AMG-tuned version of the 12-cylinder CL 600.

This twin-turbo V-12 monster produces 612 bhp and a whopping 737 lb.-ft. of toque, which Mercedes says is good for a 4.4-second (0-100-km/h mph) run. The 6.0-liter V-12 engine is coupled to a 5-speed automatic transmission, instead of the 7-speed found in the CL 63, the massive torque of the engine makes those two extra gears superfluous.

From a design standpoint, there's little to distinguish the AMG 65 from its 63 counterpart other than badging, or if you were one of the lucky 20 to secure the limited-edition AMG 40th Anniversary models, which are painted in Alubeam, a paint that makes the body look like liquid metal. In keeping with its anniversary, only 40 are being built and America gets half, a nod to the fact that the U.S. is responsible for almost 50 percent of AMG's output.

The amazing feature of the CL65 is the civility it displays in normal motoring. It has all the high-zoot accouterment found in the CL the diamond-patterned stitching in the seats is a tip-off that this is no ordinary coupe. And if you're feeling on the sporty side, there's an optional carbon-fiber trim package that applies accents made of this material both inside and outside the car.

The real nature of the beast, however, is found beneath your right foot. Floor the pedal and the CL65 surges forward with turbine-like thrust. The specially tuned exhaust lets out a satisfying growl, and objects in the rearview mirror are not only smaller than they appear, but disappear altogether quite quickly. Tweaks to Mercedes' body-control system give the car a slightly tauter and tighter ride; there's not much body roll to speak of for such a massive sedan. This is a car designed to gobble highway miles with alacrity. As a flagship for the AMG and Mercedes brands, the CL65 hits all the right notes.